Drill stem



ilatenteti Aug. 4, 1931 UNITED STATES ERD V. CROWELL, OF LOS ANGELES,CALIFORNIA DRILL STEM Application led February 2G, 1929.

This invention is a rotary drill stem for drill bits used in drillingoil wells and the like, and it is the object ot the avention to provide'for normal positive rotation of the drill bit by a string of drillpipe, while permitting yielding of 'the rotary driving connection forrelieving torsional strain when thetorqu-e ot the drill string reachesal predetermined maximum which has been calculated in accordance with adesired safety factor.

It is a it'urther object of the invention yto not only control themaximum torque of the drill string but also obstruct circulation whenthe predetermined maximum is reached, so as to indicate such conditionby the reduction in iiow of the circulating medium and thereby provide asafety device forfboth regulating and indicating excessive torque.

More particularly the invention provides a threaded engagement betweenthe drill pipe and the bit, with tensioning means normally preventingrelative axial movement at the threaded engagementand thus holding theparts against relative rotation for maintaining al positive rotarydrive, and the tensionino means adapted to yield responsive to apredetermined maximum torsional strain at the threaded engagement so asto permit relative threaded movement of the parts resulting in theirrelative rotation causing lag of the bit with relation to the drillpipe, with the pitch of the threaded engagement calculated with relationto the tensioning means so as to hold the parts against their relativethreaded movement and thus maintain the positive rotary drive until theto-rque reaches the maximum which has been determined as the limit ofsafety.

It is a further particular object of the invention to provide the drillstem with a normally open valve permitting usual circulation of a fluidas long ask the positive rotary drive is maintained, but adapted to atleast partially shut-olf circulation when there is Serial No. 342,896.

relative threaded movement between the drill pipe and the bit as aresult of excessive torsional strain, in order to indicate by theresulting partial stoppage of circulation that the predetermined maximumtorque has been reached.

Further objects of the invention will be readily understood from thefollowing description of the accompanying drawings, in which:

Fig. l is a front elevation of the drill stem partly in axial sectionand transversely severed at the line A-A, showing the normal positiverotary drive for the bit.

Fig. 2 is a 'fragmentary axial section through the drill stem, showingthe bit. lagging vvith relation to the drill pipe in accordance withexcessive torque.

Figs. 3, 4, 5 and (i are transverse sections on the correspondinglyindicated lines of Fig. l.

The drill stem is adapted for suspension from a usual string ot' rotarydrill pipe l, and preferably comprises a tubular body 2 having anextension 2 adapted to receive a bearing projection 3 et a. collar 3trom which a usual drill bit Ll is suspended. A sleeve 5 is axiallyslidable in the extension 2 but turns therewith so that it is rotated bythe string of drill pipe l, and a threaded engagement is provided betveen this rotat- 7 ing sleeve and a mandrel 7 with which the collar 3and the drill bit 4: are adapted to turn. A spring 8 normally holds therotating sleeve retracted against threaded elevation relative to mandrely7 as shown in Fig. l, so that the threaded engagement turns the mandrelwith the rotating sleeve in order to provide a positive rotary drive forthe drill bit l5 but when the torque of the drill string reaches apredetermined maximum the spring 8 is adapted to yield so as to permitthreaded movement of rotating sleeve 5 upwardly along mandrel 7 as shownin Fig. 2, thereby causing rotary lag oi the mandrel with relation tothe sleeve 5 resulting in corresponding yielding of the rotary drivingconnection for the drill bit.

Circulation through the drill string is preferably by way of a pipe 9which is adapted for axial movement with sleeve 5, :and a valve l may besuspended in body 2 so that during normal threaded retraction of thesleeve on mandrel 7 for maintaining the positive rotary drive, the valvel0 is spaced from the open end of pipe 9 as shown in Fig.

l in order to permit unobstructed circula-` tion; while threadedelevation of sleeve 5 on the mandrel'as a result of theY torque -of thedrill string overcoming the tension of spring 8, will correspondinglyelevate ypipe 9 relative to valve l() as shown in Fig. 2 so that thevalve seats in the open end of the pipe and thus at least partiallyobstructs circulation for indicating that th'eV positive rotary .drivefor the drill bit has yielded responsive to a predetermined maximumtorque.,4 v A is an instanceof ther aforementioned arrangement ofpa-rts,'tlie body 2 may be suspended'from drill pipe l by ausualthreaded connection l2, and a guide pipe'l open-at its upper end to thebore le of pipe l is preferablyV suspended in body 2 by a threadedconnection l5. The pipe 9 is adapted for telescopic reception inguidepipel, with packing 1G between pipe 9 and the bore of body 2preferably `compressed by the guide pipe against a shoulder l? in thebore of body 2 sov as to insure Aall of the circulating medium flowingdownwardly through pipe 13 and thence through pipe 9. A rthe 'valve lO'which cooperates with th open nd of pipe k9 is shown as a'usual taperning valve, preferably having hyp-passes 18 for permitting some flow ofthe circulating medium past the valve even when the valve isV seated forshuttingoll' themajor portion of the flow; and the valve is preferablysuspended from a stem 19 which may slidably project through a spider 29mounted in pipe i3, with downwardmovement ofthe valve stein limited byits head 2l Vengaging the spiderwhich lis shown as cutaway to formsuitable passages 22 for free flow of thecirculating fluid.

'llhe pipe V9 may be arranged for axial movement with sleeve 5 bythreading the lower end rof the pipe into the closed upper end of a tube25V which may bein turn threaded into a coupling collar 2G at the Lipperend of slee-ve 5; and theY spring S, which ispref# Lerably a.'relatively heavy coil spring, prefervided with grooves or'lreyways 3ladapted to lengage lcorresponding' longitudinal lugs 32 on the outersurface of sleeve 5 for rotat- Ying the sleeve with the body whilepei-initra pipe 35 preferably projecting upwardly from said open boreand telescoping in pipe 9, andthe pipe may be provided with a packingring 36 engaging the bore of pipe 9 for insuring` all of the circulatingmedium `flowing .downwardly through the bore of the mandrel. The collar3 and its bearing proj ection 3 is provided'with a bore 87 communicatingwith the vbore of themandrel and opening 'into the usual circulatingbore 38 of drill bit el for circulating a fluid in usual manner duringthe drillingoperation.

The threaded engagement between rotating sleeve 5 and the mandrel 7preferably comprises threads ll() of extremely coarse pitch on theexterior surface of the mandrel engaging corresponding vthreads il inthe bore of sleeve 5; and the tension of spring 8 is such with relationto the pitch of threads ,l0-ll as to normally hold the Vrrotating sleeveretracted on the mandrel against threaded elevation relative thereto sothat the mandrel is positively rotated with the sleeve as shown in llig. l, but the spring is adapted to yield responsive tol a predeterminedmaximum torsional strainy yat the threaded Aengagement lll-ll so'asftopermit threadedelevation of the rotating sleeve relative tothe mand-reland thus causecorresponding rotary of the mandrel with relation y toVthe rotating sleeve as shownv in Fig. 2. This rotary lag of the mandrelresults in corresponding rotary lag of drill bitl relative to the stringof rotary drill pipe l, since the sleeve 5 is rotated by the extension2EL of the tubular body 2 which is in turn rotated by drill pipell,while the mandrel 7 is fixed for rotation with the bearing projectionStof the collar 3 from which the drill bit l is suspended; andconsequently by providing any predetermined i relationship between Athetension of spring 8 and the pitch of threads 404-41-, the drill bit lwill be rotated with the drillpipe 1 as long as the torque ofthe drillvstringdoes not exceeded the predetermined 'maximuim but torque beyondsaid predetermined safety factor will cause the bit to lag relativetothe rotating dri-llV pipe in order to relievertheexcessive torque.

The bearing projection 3a of collar 3 which supports t'he'jdrill bit ispreferably ournaled in a bearing sleeve 45 which may be fixed to thelower end of body extension '2a by means 'llO of a usual threadedconnection 46, and a collar 47 is preferably threaded onto the upper endof the bearing projection 3u and rotatably seats on a shoulder 48 formedby the upper end of bearing sleeve so as to prevent axial displacementof collar 3 while permitting its rotation relative to the string ofdrill pipe for producing the desired rotary lag of the bit when t-hepredetermined maximum torque is reached. A thrust bearing comprising anannulus 49 may be provided between the bearing projection 3a and thebearing sleeve 45, and packing shown at 50 is preferably also providedbetween these relatively rotating parts. The packing 50 in conjunctionwith the packing 16 and 36 thus packs-off the bore for the circulatingmedium which extends through the drill stem, so that the threadedengagement 40-41 is shut-off from said circulating medium both above andbelow said threaded engagement, and the possibility of mud or the likeclogging the threads is thus avoided and a suitable lubricant sealedagainst escape by the packing may be provided at the threadedengagement.

Arcuate abutments 51-52I preferably project axially'from the proximateends of bearing sleeve 45 and collar 3, and are adapted forcircumferential abutment to preferably limit the relative lag of drillbit 4 to approximately one-half a revolution as will be understood by acomparison of Figs. 1 and 2; and an annular groove 53 is preferablyprovided in the end of collar 3 for reception of an axially projectingtongue 54 on the abutment 51 so as to maintain concentric alinement ofthe abutments during relative rotation of bearing sleeve 45 and collar3.

1n operation the parts are normally in the position shown in Fig. 1,with spring 8 holding the sleeve 5 in axially depressed positionrelative to mandrel 7 and against threaded elevation on the mandrel, sothat the valve 10 is spaced from the end of pipe 9 for free circulationthrough the drill stem. and the arcuate abutment 51 of bearing sleeve 45is in advance of the cooperating abutment 52 of collar 3. The tension ofspring` 8 thus holds the drill bit against rotary lag relative to thestring of drill pipe as long as the torque of the drill string does notexceed a predetermined maximum; but when the torque exceeds thepredetermined safety factor the torsional 'strain at threads 40-41overcomes the tension of spring 8 and permits threaded elevation ofsleeve 5 relative to mandrel 7. Rotation of drill pipe 1 is thuscontinued with the drill bit lagging behind. to the limit of movementpermitted by the abutment of the cocirculation advises the operatorthatl the torque of the drill string has reached the predeterminedmaximum, and at the same time the torque is relieved by the lagging ofthe drill bit relative to the rotating drill pipe.

I have thus provided extremely simple but practical means for regulatingthe torque of a drill string by a driving connection which is adapted topermit rotary lagging of the drill bit when the torque reaches apredetermined maximum, and said yielding of the rotary drivingconnection is also adapted to at least partially shut-off circulationfor indicating that the torque has reached the predetermined limit ofsafety.

I claim:

1. A drill stom comprising a body adapted by a string of drill pipe, asection fixed against axial displacement relative to the body andadapted to rotate a drill bit, and a normally non-yielding rotarydriving connection between the body and said section adapted torotatably yield in accordance with a predetermined torque of the drillstem so as to permit rotary lagging of the drill bit with relation tothe string of drill pipe.

2. A drill stem comprising relatively rotatable sections, one of whichis adapted for rotation by a string of drill pipe and the other of whichis adapted to rotate a drill bit, a ff normally non-yielding rotarydrivinj; connection between said sections adapted to rotatably yield inaccordance with a predetermined torque of the drill stem so as to permitrotary lagging of the drill bit with relation to the string of drillpipe, and means for indicating said yielding of the rotary drivingconnection.

3. A drill stein having a circulating bore and comprising relativelyrotatable sections, one of which is adapted for rotation by a string ofdrill pipe and the other of which is adapted to rotate a drill bit, anormally nonyielding rotary driving connection between said sectionsadapted to rotatably yield in accordance withpredetermined torque of thedrill stem so as to permit rotary lagging of the drill bit with relationto the string of drill pipe, and means actuated by said yielding` of therotary driving connection for retarding circulation through the saidbore.

4. A drill stem having a circulating bore and comprising a body adaptedfor rotation by a string of drill pipe, a section fixed against axialdisplacement relative to the body and adapted to rotate a drill bit, anormally non- A yielding rotary driving connection between the body andsaid section adapted to rotatably yield in accordance with apredetermined torque of the drill stein so as to permit rotarv laggingof the drill bit with relation to the string of drill pipe, and fluidtight packing for packing-olf the rotary driving connection from thecirculating bore.

5. A drill stem having a circulating bore f and comprisingrelativelyrotatable sections,

Vone'of which Vis-ad'apted for yrotation by a string of' drill'pipe andthe other ofv which isadapted to rotate a drill bit, a normally nonfyielding rotaryJ drivingconnection between said sections adapted torotatably yield in accordance with a predetermined torque ofthedrillstem', means actuated by said yielding oi the rotary drivingconnection" for retard! ing circulation through .the said bore, andymeans for ,packing-oil the rotary driving connection from the bore.

G. 'A drillstem comprising a body adapted for rotation'by a string ofdrillpipe, a section tixed against axialv displacement relative to thebody and adapted to rotate a drill bit, a normally nonfyielding rotary'driving connection between the body and said section Y mined torque ofkthe drill stem so as to permit being `v 60 rotary lagfring of the bitwith relation to the stringy of drill pipe, cooperating abutmentelements circumferentially lixed with relation to the respectivesections and adapted for circumferential abutment for limiting saidrelative lag of the bit,'and an axially extending annular tongue andgroove engagement between the abutment elements for maintain-` ing theirconcentric alinement.

8. A drill stem comprising relatively r0- tatable sections, a bodyadapted for rotation b* a string of drill aine and en aGinG one o l D bi the sections for rotating the same, the other of saidV sections beingadapted for rotation ybut lixed'against axial displacement relative tothe body and adapted to rotate a drill bit, anda normally non-yieldingrotary driving connection between said sections adapted to rotatablyyield in accordance with a predetermi ef torque of the drill stem so astopermit rotary` lagging of the drill bit with relation to the string ofdrill pipe. l

9; A drill stemfcomprising relatively ro'- tatable sections having acirculating bore, a ybody adapted'for rotation by a string oi" drillpipe and'engaging one of the sections for rotating the same, the otherof said sections adapted for rotation but tixed against axialdisplacement relative to the body and adapted torotate a drillv bit, anormally non-yielding rotary driving connection between said sectionsadaptedtoro` tatably yield in accordance with a pred-etermined'torqueofthe drill stem lso as to permitk connection.

rotary lagging of' the drillbit with relation to the spring of drillpipe, and packing between the body and the circulating bore of thesections forv packing-oill the rotary driving l0, Al drill`stemcomprising relatively rotatable sections, a; body adapted' forrotation by a string of drill pipe 'and engaging one of thev sections:tor rotatingfthe saine, the other of .said sections ,being adapted forrotation but ixed against axial displace`- ment relative to thel bodyand ladapted to rotate drill bit, a normally non-yielding rotarydriving' connection betwen said sections adapted to rotatably yieldinaccordance with a predetermined'torque of the drill stem so as topermit rotarylagging of said other section with relation to the body,and cooperating abutment elements Viixcd relative to the body and saidother section and adaptedk 'for circumferential abutment Jfor limitingthe relative lag of said other section.

l1. A drill stem comprisingrelatively rotatable sections, a body adaptedfor rotation by a string of drill pipe and engaging one of the sectionsfor rotating the same while permitting axialv movement of said sectionrelative ktothe kbody, saiov section constituting a drive section, theother otfsaid sections being lixed against axial displacement` relativeto the body and adapted to rotate a drill bit, saidsection .constitutinga driven section,.a threaded engagement between the sections, and meansfor normally tensioning .a

the drive section against axial movement relative to the body so as tohold the `sect-ions againstl relative `threaded movement and thusmaintain a positive rotary .driving connection between the sections, thersaid tensioningV means bcing adapted' to yield in accordance with apredetermined torque of the drill stem in order to permit axialmovementl oi the drive section relative to the body for relativethreaded movement between the sections causing yielding of the rotarydriving connection and lagging of the bit with relation to the stringofv drill pipe. s

1Q. A drill stem comprising relatively rotatable sections having acirculating bore, a body adapt-ed for rotationl by a string of drillpipe and engaging one of thel sections for rotating the Vsame whilepermitting axial movement'o'f said section relative to the body, saidsection constituting aV drive section,'the other of said, sections beingfixed against axial displacement relative tothe body andadapted torotate a drill bit, said section constituting a drivenV section, means1f! Vlor normally tensioning the drive section against axial movementrelative to the body,

Va( driving connection between 'the sections heldf'against yielding bysaid non-movement of the drive section relative to the body, the

said tensioning means being adapted to yield in accordance with apredetermined torque of the drill stem in order to permit axial movementot the drive section relative to the body, said movement of the drivesection causing rotary yielding of the driving connection and lagging otthe drill bit with relation to the drill pipe, and a valve mounted inthe body and normally spaced from the circulating bore or" the drivesection so as to permit unobstructed circulation but arranged wherebyaxial movement of the drive section relative to the body in response toyielding of the tensioning means is adapted to seat the valve in thecirculating bore of the drive section for obstructing circulation.

13. A drill stem comprising relatively rotatable sections having acirculating bore, a body adapted for rotation by a string of drill pipeand engaging one oi' the sections for rotating the same While permittingaxial movement of said section relative to the body, said sectionconstituting a drive section, the other of said sections being fixedagainst axial displacement relative to the body and adapted to rotate adrill bit, said section constituting a driven section, means for normally tensioning the drive section against axial movement relative tothe body, a driving connection between the sections held againstyielding by said non-movement ot' the drive section relative to thebody, the said tensioning means being adapted to yield in accordanceWith a predetermined torque of the drill stem in order to permit axialmovement of the drive section relative to the body, said movement of thedrive section causing rotary yielding of the driving connection andlagging of the drill bit with relation to the drill pipe, a pipeprojecting upwardly from the bore of the drive section, and packingbetween said pipe and the body.

14. A drill stein comprising relatively rotatable sections having acirculating bore, a body adapted for rotation by a string of drill pipeand engaging one of the sections for ro tating the same while permittingaxial movement of said section relative to the body, said sectionconstituting a drive section, the other oi said sections being iixedagainst axial displacement relative to the body and adapted to rotatedrill bit, said section constituting a driven section, means lornormally tensioning the drive section against axial movement relative tothe body, a driving connection between the sections held againstyielding by said non-movement of the drive section relative to the body,the said tensioning means being adapted to yield in accordance with apredetermined torque of the drill stem in order to permit axial movementof the drive section relative to the body, said movement of the drivesection causing rotary yielding of the driving connection and lagging ofthe pipe projecting upwardly from the bore of the drive section, a pipeprojecting upwardly from the bore of the driven section and telescopingin the irst men tioncd pipe, and pack-` ing between said pipes.

l5. A drill stem comprising relatively rotatable sections having acirculating bore, a body adapted for rotation by a stringl ot dri-llpipe and engaging one of the sections tor rotating the saine whilepermitting axial infwenienl. ci said section relative tothe body, saidsection constituting a drive section, the other said sections beingadapted for rotation but lined against axial displacement reiative tothe body and adapted to rotate a drill bit. a normally non-yieldingrotary driving connection between said sections adapted to rotatablyyield in accordance with a predetermined torque of the drill stem so asto permit rotary lagging of the drill bit with relation to the string otdrill pipe, the rotary driving connection being arranged whereby itsyielding will axially shift the drive section relative to the body, anda valve mounted in the body and normally spaced from the circulatingbore of the drive section so as to permit unobstructed circulation butarranged whereby said axial shifting et the drive section relative tothe body is adapted to seat the valve in said circulating bore forobstructing circulation.

16. A drill stem comprising relatively rotatable sections having acirculating bore, a body adapted for rotation by a string of drill pipeand engaging one et the sections for rotating the same, the other otsaid sections being adapted for rotation but fixed against axialdisplacement relative to the body and adapted to rotate a drill bit, anormally nonyielding rotary driving connection between said sectionsadapted to rotatably yield in accordance with a predetermined torque ofthe drill stein so as to permit rotary lagging oi the drill bit withrelation to the string oi' drill pipe, and packing between the body andsaid sections axially beyond the rotary driving connection.

17. A drill stem comprising relative rotatable sections, one of whichadapted for rotation 'by a string of drill pipe and the other of whichis adapted to rotate a drill bit, a nor-- mally yielding rotary drivingconnection between said sections adapted to rotatably yield inaccordance with a predetermined torque of the drill stem so as to permitrotary lagging of the bit with relation to tlie string ot drill pipe,cooperating abutment elements circumferentially fixed with relation tothe respective sections and adapted for circumferential abutment torlimiting said relative lag of the 18. A drill stein comprising a bodyadapted for rotation by a string of drill pipe, a section fixed againstaxial displacement relative 6 s ,.81 "meer to the bodyy and adaptedv torotate a drill bit, v

the body and said section having normally vcommunieating circulatingbores, fluid tight packng'means ybetween the body and said section, anda normally non-yielding rotary driving connection between the' body andsaid section adapted'to rotatably yield in accordance' With apredetermined torque of the drill stem so as to permit rotary lagging ofthe drill bit with relation tothe string of drill pipe.

In testimony whereof he lhas affixed his signature. Y

ERD V. GROWELL.

CERTIFICATE 0F CORREC'UON.

Patent No. 1,817,067. Granted August 4, 1931, to

ERD V. CROWELL.

It is hereby certified thaterror appears in the printed specification ofthe above numbered patent requiring lcorrection as follows: Page 3, line82, ciaim 1, after "adapted" insert for rotation; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 29th day of September, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.

